Work

Spatial heterogeneity of nonlinear signals, background noise and vertical velocities in GNSS vertical time-series across the Tibetan Plateau

Year: 2026

Type: article

Abstract: SUMMARY This study quantifies the spatial heterogeneity of nonlinear signals, background noise and vertical velocities in Global Navigation Satellite System (GNSS) vertical time-series across the Tibetan Plateau (TP), using multisource loading corrections to isolate tectonic deformation. We analysed 20 yr of GNSS data (2002–2021) from Crustal Movement Observation Network of China and Nevada Geodetic Laboratory networks, processed via GipsyX and referenced to ITRF2014. Non-tidal atmospheric, oceanic and hydrological loading effects were applied utilizing operational models from Gravity Recovery and Climate Experiment (GRACE) mascon data (Center for Space Research/Jet Propulsion Laboratory/Goddard Space Flight Center), followed by common mode error (CME) filtering. The findings highlight significant spatial heterogeneity: Monsoon-dominated southern TP exhibits 10–20 per cent Root Mean Square (RMS) reduction after non-tidal atmospheric-oceanic (AO) loading corrections, while northern TP shows minimal improvement (<10 per cent), highlighting non-atmospheric noise dominance. Integration of AO and GRACE-modelled hydrological (AOG) loading corrections outperform AO+hydrological (AOH) model, achieving 25–35 per cent RMS reduction in glacier-covered Himalayas by resolving cryospheric mass loss. Spectral and principal component analysis analyses confirm AOG’s superiority in suppressing interannual signals (PC1 variance: 62.7 per cent versus AOH’s 60.3 per cent), particularly in monsoon-ENSO (El Niño-Southern Oscillation)-affected regions. Noise modelling demonstrates high-spatiotemporal correlations (63.1 per cent white noise, WN + FN in raw data), with flicker noise (FN > 5.2 mm) linked to seismic activity in southeastern TP and power-law noise (PL > 3.5 mm) to permafrost dynamics in the north. Post-AOG_CME processing simplifies noise structures (WN + Generalized Gauss-Markov dominance: 32.9 per cent), reducing velocity uncertainties by 26.9 per cent and revealing a residual +1.2 mm yr−1 uplift in the southern inner TP, indicative of mid-crustal flow. Persistent uncertainties (>0.55 mm yr−1) along the Himalayan thrust front correlate with deep lithospheric boundaries. Our findings demonstrate the necessity of integrating GRACE-derived corrections with CME filtering to accurately delineate tectonic signals within the intricate suture zones of the TP, offering crucial insights into plateau-wide geodynamic processes.

Source: Geophysical Journal International

DOI: 10.1093/gji/ggag104